U.S. Olympians will have to make do without the team’s official yogurt depriving them of a source of protein and potentially disturbing their daily routines as they prepare for the biggest competition of their lives.

Some 5,000 cups of Greek yogurt from Team USA sponsor Chobani isn’t getting to Sochi because of a customs dispute with Russia.

U.S. halfpipe skier Aaron Blunck said Friday that to traveling athletes, getting food from home is part of feeling fit and healthy. “And having the yogurt there, that helps you, gives you protein, gives you nutrition,” he said.

But teammate Lyman Currier said part of being an elite athlete is dealing with the unexpected, “so whether we have our yogurt or not, we’ll be able to adapt.”

“We all have different routines before competing but I think that part of the sport is adapting,” he said. “So whether we have our yogurt or not, we’ll be able to adapt.”

Russian authorities say the U.S. Department of Agriculture has refused to provide a certificate that is required for dairy products under its customs rules.

“American officials know what the requirements are, and I do not understand why they stood to the side and waited until the situation reached this point,” said Alexei Alexeyenko, an official at the Russian Federal Service for Veterinary and Phytosanitary Surveillance. “This question can be resolved very quickly.”

U.S. Sen. Charles Schumer this week implored the Russians to let the shipment through and said export trade rules should have nothing to do with it, since the yogurt isn’t for sale and is to be eaten only by U.S. citizens in Sochi.

U.S. Ambassador to Russia Michael McFaul said Friday the trade dispute goes back four years and that he’s been working on it ever since he arrived as ambassador in 2012.

“Unfortunately, with this particular shipment, it came to an impasse,” he said. “We are still working it, we would like our athletes to be able to have the American yogurt.”